AR-V7–Positive Prostate Cancer: Phase II Trial of Combination Immunotherapy
Posted: Wednesday, May 19, 2021
Results from a phase II nonrandomized clinical trial, published in The Prostate, revealed “only modest” activity in patients with AR-V7–expressing metastatic castration-resistant prostate cancer treated with nivolumab plus ipilimumab. According to Emmanuel S. Antonarakis, MD, of Johns Hopkins University School of Medicine, Baltimore, and colleagues, their findings were insufficient to justify further exploration of this agent in unselected patients with this aggressive phenotype.
A total of 30 patients with progressive prostate cancer and detectable AR-V7 transcripts were enrolled in the study. Patients in cohort 1 (n = 15) were treated with 3 mg/kg of nivolumab plus 1 mg/kg of ipilimumab every 3 weeks for four doses. Treatment was followed with a maintenance regimen of 3 mg/kg of nivolumab every 2 weeks. The second cohort (n = 15) received the same treatment but included patients who previously experienced disease progression on enzalutamide monotherapy and continued their treatment.
The authors reported a prostate-specific antigen response rate of 2 of 15 in cohort 1 and 0 of 15 in cohort 2. The overall response rate was 2 of 8 for cohort 1 and 0 of 9 for cohort 2. Progression-free survival was reported to be 3.7 months in cohort 1 and 2.9 months in cohort 2, and median overall survival was 8.2 and 14.2 months, respectively. The researchers found that 3 of 15 patients in cohort 1 and 4 of 15 patients in cohort 2 achieved a progression-free survival of more than 24 weeks.
The authors further noted that in the combined cohort, it appeared that patients with lower alkaline phosphatase levels and higher circulating interleukin-17 (IL-17) had greater overall survival.
Finally, both cohorts exhibited similar results regarding safety, with 7 of 15 patients in cohort 1 and 8f of 15 patients in cohort 2 exhibiting grade 3 or 4 adverse events.
Disclosure: For full disclosures of the study authors, visit wiley.com.
